1. Field of the Invention
The present invention relates to a chain guide having a guide shoe that slidably guides a chain, and a reinforcing unit that reinforces the guide shoe.
2. Description of the Related Art
It has been common practice to use a chain guide having a guide shoe that slidably guides a running chain to stabilize a chain running between sprockets and to keep an appropriate chain tension. As a system that uses this chain guide, for example, an engine timing system is known, wherein an endless timing chain runs over sprockets of a crankshaft and cam shafts inside an engine room. A chain guide is used to guide this endless timing chain passing over a drive sprocket of the crankshaft and a pair of driven sprockets of the cam shafts inside the engine room.
Guide rails of chain guides used in such known timing systems should preferably be made of a low-friction, high wear-resistance material, and therefore a guide entirely made of a low-friction resin material is known. On the other hand, the chain guide needs to have certain levels of strength, rigidity, and durability to be able to withstand the tension or vibration of the chain and to guide the chain stably. If the chain guide is made solely of a resin material, it needs to have a larger material thickness to achieve necessary strength, rigidity, and durability, and will end up occupying a larger space inside the engine room. Therefore, some known chain guides have their guide rail made of a low-friction resin material and reinforced with a material with high strength, rigidity, and durability such as metal, so as to reduce the occupying space while securing necessary strength, rigidity, and durability of the chain guide as a whole.
One of such known chain guides is formed by a guide shoe that slidably guides a running chain and a plate that reinforces the guide shoe along the guide longitudinal direction. The guide shoe has a plate holding part in the form of a slit-like groove, into which the plate can be inserted from a lower side thereof, on the backside of the guide rail. With the plate having high rigidity and durability being inserted into the plate holding part from below, the occupying space of the chain guide is reduced, while necessary strength, rigidity, and durability are secured as a whole (see Japanese Patent Application Laid-open No. 2015-025535).